A hydrocarbon steam reforming process is carried out in a combustion chamber of a reforming furnace comprising burners and tubes filled with catalysts that are capable of being passed through by a mixture of hydrocarbons and steam. The burners are positioned so as to transfer the heat from their combustion to the mixture of hydrocarbons and steam through the wall of the tubes, generally by radiation of the heat from the flame to the refractory walls of the combustion chamber.
The reformer tubes usually have a service life of around 100 000 hours under normal operating conditions.
Temperatures that are higher than anticipated reduce the service life of the tubes: thus, the service life may be halved if the tube is used at a temperature of 10 to 20° C. above its design temperature or DTT (design temperature of the tube).
However, high temperatures are still desirable for increasing the syngas production yield.
Consequently, it is necessary to control the method used in the furnace so as to use a high temperature that allows a high yield of syngas while making sure that this temperature does not reduce the service life of the reforming tubes. The temperature DTT−15° C. is considered to be the maximum temperature at which the reforming furnace can be used without risk, this maximum operating temperature is also referred to as MOT.
The objective of the present invention is to provide such a method of control.